High-speed brightness switching for static type constant current regulators



July 1, 1952 A J HAUCK 2,602,150

HIGH-SPEED BRIGHINE SS SWITCHING FOR STATIC TYPE CONSTANT CURRENT REGULATORS Filed Jan. 11, 1950 2 SHEETS-SFEET '1 I 'VVEN TOR.

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y 1, 1952 A. J..HAUCK 2,602,150

- HIGH-SPEED BRIGHTNESS SWITCHING FOR STATIC TYPE CONSTANT CURRENT REGULATORS Filed Jan. 11, 1950 2 SHEETS--SHEET 2 INVENTOR. W0 mcLdPoM/c/Q BY v Patented July 1, 1952 HIGH-SPEED BRIGHTNESS SWITCHING. FOR. STATIC TYPE CONSTANT CURRENT" REG- ULATORS Aloysius- J Hauck; Milwaukee, Wis., assignor to Hevi Duty Electric Company, Milwaukee, Wis.,

a corporation of Y Wisconsin Application January 11, 1950; Serial No". 137,970-

8* Claims; 1.

My invention relates broadly to electric control systems and more particularly to a constant current regulating system for lighting andthe' like;

One of the objects of my invention is to provide an electric control system in which the values of the currents supplied to the load circuit can be varied at will.

Another object of my invention is to provide an electric regulating system in which current variations may be produced with the system under load.

Still another object of my invention is to provide' an electric control system where changes can be made in output current without visual blackening. of the lights in the load circuit.

A still further object of my invention i to provide an electric control system for changing the value of the current to a load circuit while at the same time preventing more than one relay of the, control system to close its contacts at any one time.

These and other objects and advantages of the invention will be more readily apparent from the specification hereinafter following by reference to the accompanying drawings in which:

Fig. 1 shows a schematic circuit arrangement for an electric control system embodying my invention; and

Fig. 2 shows a modified form of circuit employing my invention.

Referring to Fig. 1 of the drawings, the control system shown is adapted to control a load circuit indicated at 16 including a plurality of electric lamps in series for street lighting, air port lighting and the like. Power is supplied from a; supply circuit I which may be any convenient source of alternating current. The supply circuit is connected to transformer l4 having a series of taps thereon connected to the opposite corners of a monocyclic square including a pair of inductive reactors l3 and a pair of condensers [2. The transformer i4 may be adjusted through the taps 2 to compensate for any changes inthe supply voltage so that the monocyclic square will always be supplied with a substantially constant potential and will convert the constant potential into a constant current. It is further understood that the taps in the secondary of transformer [4 are subject to change at the will of the operator by interconnection with contactors 6 constituting interlocks 31-35 and operation of snap switch A operative over contacts I", 2', 3", 4' and 5', thus varying the voltage to the mono'cyclic square. It will be understood that while a monocyclic square is shown other 2. types of constant potential to constant current resonant circuitsmight-be employed. The-res.- onant circuit is connected to the primary wind ing of transformer [5 whose output is converted toa current value at leads l9- sufficient to operate the lights l6 as desired;

A current transformer II is placed in the cir-- cult of a secondary ofoutput transforme-r l5 and provides theproper current to ammeter I0 for'visual indication of the value-of the'current at leads [9. Open circuit protection is provided by installing an overcurren-t relay 8" in the sec ondary of current transformer I. The primary of this current transformer is equipped for an extension so that even at the lower voltages sufficient current is produced in relay 8- to close its contacts. Relay 9 is connected in series with the holding coil of primary switch 3; On-off" control switch 5 which opens or'closes' the circuit to the primary switch 3 operates in conjunction with relay 9 for the purpose of energizing the regulating system and resetting relay 9 in case it has been tripped by an open circuit in" the load.

The snap switch 4 is located either adjacent to. or remote from the regulating apparatus and serves the purpose of providing means for the operator of changing from one tap" to the other thereby" producing variations in the. output current to load circuit [6 and thus changing the brightness of the lights.

Fig. 2 shows a modified circuit arrangement embodying my invention in' which an alternate to snap switch 4 is" provided in theform of a shorting type switch I! operative over'contacts I", 2", 3", 4", 5",.6, 1", 8" and 9 which hasa manual' interlock in the on-off switch circuit 5 and operates in connection with relay [8.

In operation this system functions as follows: Referring to Fig. 1, when the need for lightsis apparent, an operator closes on-off switch 5 which in turn closes the circuit to the holdin coil of primary switch 3 through power obtained from lines 20. This closes the primaryci'rcult to transformer 14 of the regulating system: and turns on the lights of the load system 16. Inasmuch as control snap switch 4' will be atone setting or the other, for example 5, contactor B5 of the control system will be closed. This allows current to flow to the lights at [6' at the full output as controlled by the output of transformer Hi. If it is desired to reduce the brightness of the lamps at IB it is necessary to reduce the voltage to the monocyclic square thu reducing the current flowing to the lamps [6. To do this the operator changes the setting of snap switch 4 from to, for sample, 4. When this change is made contactor B5 is de-energized and drops back into place closing all the contacts of the four interlocks. As soon as the interlock contacts are closed, it is possible for current to flow through the holding coil of contactor B4 thus moving it into a closed position and opening the interlocks 6 connected in the circuits to the other contactors. Inasmuch as the tap connected with contactor B4 produces a lower VOltage to the monocyclic square, a corresponding reduction in current will flow to the load circuit l6, making a corresponding reduction in the brilliance of the lamps.

From this system it can be seen that only one contactor may be closed at one time because of the interlock contacts involved. Successive taps may be changed in the same manner.

Because of the quick change feature of snap switch l and the relatively short drop out time between the opening of one contactor and closing of the second contactor very little time has elapsed and is of such short duration that the filaments of the lamps it have not had a chance to show any visible blackening. A result of this is to provide non-interrupted illumination during switching periods.

When an open circuit occurs in load circuit it, it is reflected in an increase in current to the primary of a monocyclic square. The secondary of transformer l is in series with the coil of current relay 8 which has normally open con tacts. As the current rises in the primary of tranfsormer 1 thus causing a similar rise in the secondary, the relay 8 closes its contacts. As these contacts close, they actuate the holding coil of relay 9 which has one normally open and one normally closed contact. As the normally closed contact of a relay 9 opens, the circuit to primary switch 3 is opened thus de-energizing the equipment. At approximately the same time but with a slight lag, the normally open contacts of relay 5] close, thus sealing the current to the holding coil of relay 9 and keeping it in that position until such time as it is reset by the opening of on-off switch 5. Thus the cirlcuit is de'-ene'rgized in case of an open in the load circuit IS and cannot be energized until ""on-off switch 5 is opened and reclosed.

The alternate means of switch ll, shown in Fig. 2, operates in substantially the same manner except that the switch is of the shorting type thus necessitating use of a mechanical interlock and a relay [8 with normally open contacts. In operation the contact of switch I! is moved for example from 5 to 5. Because of the interlocks on contactors 6 of the circuit, only one contactor can be energized at one time. Thus'when the shorting type contact leaves contact 5", contactor B5 drops out and contactor B5 is energized as soon as the interlocks on contactor B5 are closed.

The manual interlock on switch ii is a safety precaution in case switch il may be left in position between two contacts'when the circuit is ale-energized. Thus when the current is turned on, the manual interlock is open when the switch bridges two points of contact and no damage can occur when two contactors 6 close simultaneously. As it is undesirable tohave the circuit to the primary switch holding coil open during normal switching when the equipment is energized, a relay It with normally open contacts is placed in the circuit and this relay is closed during normal operationof the equipment.

Wherever in the specification and/or claims I have referred to incandescent lamp I desire that it be understood that any form of luminous device is intended and that the term incandescent lamp has been used as embracive of mercury vapor, sodium vapor, fluorescent lights and electronic devices.

I have also specifically referred to a monocyclic square constant current regulator in the specification and claims and I desire that it be understood that this term is intended to include a multiple circuit system of any type to perform an equivalent function of the monocyclic square constant current regulator.

While one embodiment of the invention and a modification of same has been shown and described in detail herein, I desire that it be understood that I do not intend my invention to be limited to the exact circuits shown and that the circuits described are to be considered as illustrative only and not as a definition of the scope of the invention, reference being had for that purpose to the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is as follows:

1. A control system for incandescent lighting circuits which comprises a series circuit includa multiplicity of incandescent lamps, an alternating current power supply source, means for applying alternating current from said alternating current power supply source to saidseries circuit in step by step increments of differing current amplitudes, a control switch movable to successive contact positions through a drop out time of relatively short duration, each of said positions corresponding to a predetermined current amplitude condition in said series circuit, and interlock circuit interposed between said alternating current power supply source and the aforesaid means for maintaining the application of energy to said incandescent lamps at the individual current amplitude steps and effecting the cessation of one current amplitude step prior to the application of a succeeding current amplitude step and at a rate for maintaining the visible illuminosity of said incandescent lamps without appreciable blackening or visibility during the change in position of said control switch and application of differing current amplitudes to said series circuit.

2. A system for brightness switching for an incandescent light system comprising a load circuit including a multiplicity of incandescent lamps, a power source of alternating current, a pair of transformer systems, each of said transformer systems including primary and secondary windings, with the primary winding of one of said transformer systems connected with said power source of alternating current, a monocyclic square having input and output circuits, the output circuit of said monooyclic square being connected with the primary winding of said other transformer system, the secondary winding of said last mentioned transformer system being connected with said load circuit, means interconnecting the secondary winding of said first mentioned transformer system with the input circuit of said monocyclic square including a multiplicity of' circuits for changing the current amplitude supplied to said load circuit in steps, and a control switch movable by increments to successive contact positions corresponding to the number of said circuits for changing the current amplitude supplied to said load cirq it thr h drop out times or re ativsly shor duration for controlling the rate of change of said steps whereby illuminosity of said incandescent lamps may be continuously maintained and without any visible blackening of the incandescent lamps during the said changes the drop out time of said control switch and during the changes in current amplitude in said load circuit.

3. A system for brightness switching for an incandescent light system comprising a load circuit including a multiplicity of incandescent lamps, a power source of alternating current, a pair of transformer systems, each of said transformer systems including primary and secondary windings with the primary winding of one of said transformer systems connected with said power source of alternating current, a circuit for converting substantially constant potential into substantially constant current, said circuit including an input system and an output system, connections between the output system of said circuit and the primary winding of said second mentioned transformer system, connections between the secondary winding of said last mentioned transformer system and said load circuit, means interposed between the secondary winding of said first mentioned transformer system and said input system for successively applying voltage of differing amplitudes to said input sys tem for correspondingly controlling the operation of said load circuit at differing current amplitudes, and a control switch movable to successive contact positions spaced from one another through drop out times of relatively short duration where said contact positions are electrically connected with spaced taps in the secondary winding of said first mentioned transformer system for controlling the rate of operation of said last mentioned means for maintaining said load circuit substantially continuously energized and without appreciable visible blackening of the incandescent lamps during the periods of change in position of said control switch and in the change in current amplitude applied to said load circuit.

4. A system for brightness switching for an incandescent light system as set forth in claim 3 in which said first mentioned means comprises an interlock circuit for effecting the application of current to said input system at a selected current amplitude while blocking the application of current to said input system at other current amplitudes while the selected current amplitude is being applied to said input system.

5. A system for brightness switching for an incandescent light system as set forth in claim 3 in which said first mentioned means is constituted by a multiplicity of coacting interlock circuits for applying current of a selected amplitude to said input system selectively, while preventing the concurrent application of current of differing amplitude thereto, and in which the control switch renders effective individual interlock circuits for selectively controlling the application of current of predetermined amplitudes to said load circuit through time intervals too short to effect visual blackening of said incandescent light system.

6. A system for brightness switching for an incandescent light system as set forth in claim 3 in which said first mentioned means is constituted by a multiplicity of electrical interlock circuits for controlling the energization of said input system at an individual selected current amplitude and in which said control switch includes a manually controllable member and in which said contacts are individual to the aforesaid multiplicity of electrical interlocks, and an interlock on said switch for restricting the position thereof with respect to said contacts.

'7. A system for brightness switching for an incandescent light system as set forth in claim 3 in which said control switch is connected with a multiplicity of individual controllable interlock switches for individually controlling the application of differing current amplitudes to said input system, and a reset circuit for restoring said interlock switches subsequent to each operation thereof.

8. A system for brightness switching for an incandescent light system as set forth in claim 3 in which said first mentioned means is constituted by a multiplicity of individual interlock switches for controlling the application Of voltage at differing amplitude to said input system and in which said control switch includes a manually operable switch controller and where said contacts are individual to each of said interlock switches, a manual interlock associated with said last mentioned manually operable switch, and an overcurrent relay for interrupting the circuit between said power source of alternating current and the primary winding of said first mentioned transformer systems at a predetermined current amplitude.

ALOYSIUS J. HAUCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,226,041 Young et al Dec. 24, 1940 2,405,837 Lang Aug. 13, 1946 2,445,577 Haug July 20, 1948 FOREIGN PATENTS Number Country Date 279,212 Great Britain Oct. 27, 1927 

